The battle of Sekigahara, fought in 1600 at a crossroads in Japan, unified that nation under the Tokugawa family for more than 250 years.
Sekigahara allows you to re-contest that war as Ishida Mitsunari, defender of a child heir, or Tokugawa Ieyasu, Japan's most powerful daimyo (feudal lord).
The campaign lasted only 7 weeks, during which each side improvised an army and a strategy with what forces their allies could provide. Each leader harbored deep doubts as to the loyalty of his units - for good reason. Several daimyo refused to fight; some even turned sides in the midst of battle.
To conquer Japan you must do more than field an army - you must be sure it will follow you into combat. Cultivate the loyalty of your allies and deploy them only when you are confident of their allegiance. Win a battle by gaining a defection from the ranks of your opponent.
Don't just take our word for it! Check out this review of Sekigahara: The Unification of Japan: